comparison: src/cx/hash_map.h
src/cx/hash_map.h
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| 1 /* | |
| 2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. | |
| 3 * | |
| 4 * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved. | |
| 5 * | |
| 6 * Redistribution and use in source and binary forms, with or without | |
| 7 * modification, are permitted provided that the following conditions are met: | |
| 8 * | |
| 9 * 1. Redistributions of source code must retain the above copyright | |
| 10 * notice, this list of conditions and the following disclaimer. | |
| 11 * | |
| 12 * 2. Redistributions in binary form must reproduce the above copyright | |
| 13 * notice, this list of conditions and the following disclaimer in the | |
| 14 * documentation and/or other materials provided with the distribution. | |
| 15 * | |
| 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | |
| 17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE | |
| 20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
| 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | |
| 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | |
| 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | |
| 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
| 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
| 26 * POSSIBILITY OF SUCH DAMAGE. | |
| 27 */ | |
| 28 /** | |
| 29 * \file map.h | |
| 30 * \brief Interface for map implementations. | |
| 31 * \author Mike Becker | |
| 32 * \author Olaf Wintermann | |
| 33 * \version 3.0 | |
| 34 * \copyright 2-Clause BSD License | |
| 35 */ | |
| 36 | |
| 37 #ifndef UCX_HASH_MAP_H | |
| 38 #define UCX_HASH_MAP_H | |
| 39 | |
| 40 #include "map.h" | |
| 41 | |
| 42 #ifdef __cplusplus | |
| 43 extern "C" { | |
| 44 #endif | |
| 45 | |
| 46 /** Internal structure for a key within a hash map. */ | |
| 47 struct cx_hash_map_key_s { | |
| 48 /** The key data. */ | |
| 49 CxDataPtr data; | |
| 50 /** The hash value of the key data. */ | |
| 51 unsigned hash; | |
| 52 }; | |
| 53 | |
| 54 /** Internal structure for an element of a hash map. */ | |
| 55 struct cx_hash_map_element_s { | |
| 56 /** The value data. */ | |
| 57 void *data; | |
| 58 | |
| 59 /** A pointer to the next element in the current bucket. */ | |
| 60 struct cx_hash_map_element_s *next; | |
| 61 | |
| 62 /** The corresponding key. */ | |
| 63 struct cx_hash_map_key_s key; | |
| 64 }; | |
| 65 | |
| 66 | |
| 67 /** | |
| 68 * Creates a new hash map with the specified size using a UcxAllocator. | |
| 69 * | |
| 70 * @param allocator the allocator to use | |
| 71 * @param buckets the initial number of buckets in this hash map | |
| 72 * @return a pointer to the new hash map | |
| 73 */ | |
| 74 CxMap *cxHashMapCreate( | |
| 75 CxAllocator *allocator, | |
| 76 size_t buckets | |
| 77 ); | |
| 78 | |
| 79 /** | |
| 80 * Increases the number of buckets, if necessary. | |
| 81 * | |
| 82 * The load value is \c loadFactor*buckets. If the element count exceeds the load | |
| 83 * value, the map needs to be rehashed. Otherwise, no action is performed and | |
| 84 * this function simply returns 0. | |
| 85 * | |
| 86 * The rehashing process ensures, that the number of buckets is at least | |
| 87 * \p bucketFactor times the number of stored items. So there is enough room for additional | |
| 88 * elements without the need of another soon rehashing. | |
| 89 * | |
| 90 * You can use this function after filling a map to dramatically increase access performance. | |
| 91 * | |
| 92 * @note If the specified map is not a hash map, the behavior is undefined. | |
| 93 * | |
| 94 * @param map the map to rehash | |
| 95 * @param loadFactor a percentage threshold for the load of the map | |
| 96 * @param bucketFactor a factor for the number of buckets that shall be available after rehashing | |
| 97 * @return zero on success, non-zero if a memory allocation error occurred | |
| 98 */ | |
| 99 __attribute__((__nonnull__)) | |
| 100 int cxMapRehash2( | |
| 101 CxMap *map, | |
| 102 float loadFactor, | |
| 103 float bucketFactor | |
| 104 ); | |
| 105 | |
| 106 /** | |
| 107 * Rehashes the map with load factor 0.75 and bucket factor 2.5. | |
| 108 * | |
| 109 * @param map the map to rehash | |
| 110 * @return zero on success, non-zero if a memory allocation error occurred | |
| 111 * @see cxMapRehash2() | |
| 112 */ | |
| 113 __attribute__((__nonnull__)) | |
| 114 static inline int cxMapRehash(CxMap *map) { | |
| 115 return cxMapRehash2(map, 0.75f, 2.5f); | |
| 116 } | |
| 117 | |
| 118 | |
| 119 #ifdef __cplusplus | |
| 120 } // extern "C" | |
| 121 #endif | |
| 122 | |
| 123 #endif // UCX_HASH_MAP_H |
